Yes, Zinn argument is convincig. His explanation is that the US got into the war because England was growing in the market for palling American goods where America invested money in the form of interest loans. For example, JP Morgan and Company acted as agents for allies in order to be able to borrow a large amount of money and make the profit from the war, and to connect US finances in the interests of the British victory over Germany.
Otherwise, it's hard to believe that America has entered the war because of sinking passenger ships with American and British passengers, so this excusion even more corroborates Zinn's argument.
